This looks like a promising free service that seems to offer all the benefits of a good TEnT, but delivered through a Web 2.0 interface. Visit this link for a full list of features.
There is a short review about Lingotek on Translator Support.
One concern with this service, however, is that you cannot export your own TM’s, so if for any reason you have to switch your project to another tool, all you can do is export single documents in the XLIFF format. If you want to export the whole TM you are pretty much stuck.